Whats your budget? Do you have an amp? Can you solder? Do you currently own speakers?
Short version: Headphone budget is up to $3000, but I could stretch. Headphone amp budget has been raised to $3500 or so. I have a borrowed headphone amp from a local (and kind) Head-Fi-er. I have two two-channel amps sitting around, an Adcom _____ that is 60 wpc (not integrated) and a Quad 405 II, upgraded at the factory in England (twenty years ago) that is maybe 100 wpc. I don't solder but I have a nephew that does - but if I am honest I don't really want a project. I have Thiel CS2 speakers for my two-channel system; nowhere in this house to put them.
For this Headphone-only System: I have a Cary DMS-500 Streamer/DAC, and an old Linn Genki CD player which I use as a transport; it has just one coax digital output which is sufficient (and significantly better than zero digital outputs!). No computer, no NAS. I'm only adding a headphone amp and headphones (and a nice Braddington-Young leather recliner that I have to retrieve from my Mom's house).
More info:
My budget for headphones started out at $1700. But six months later the new HEK v2 headphones came out, and instead of planning to buy used, as I sometimes do, I upped the number to $3000 less any small discount one might receive, for the HEK v2 headphones.
I would like my headphone budget to remain around $3000 since I've also moved from "needing" a $2000 headphone amp like the MicroZotl MZ2 or the Dragon Inspire IHA-1 to mid-$3000 amps like the MicroZotl MZ3, the Woo Audio WA5-LE, or some other tube-based amplifier with (probably) an outboard power supply. I am partial to the planer magnetics; otherwise the option of the Focal Utopia, spend even more money and forget about the cash and enjoy the music, would be a quick and easy and sensible (sound quality wise) choice.
I like my current home, but it has a large family room that is not at all suitable for a decent two-channel system (in fact, it is getting a superior three-channel passive soundbar with Anthem Receiver and a sealed subwoofer with wireless "kit" optimally placed (optimal equaling: wherever my wife says it is acceptable).
I am not interested in an electrostatic system - at $6000 they are too expensive. (Wait, my headphone plus amp budget has crept up to $6500?)
I plan to use some kind of tube-based headphone amp; I'm leaning towards the MZ3 partly because it runs cool and tubes last "forever", which maybe means two or three years...